Thermal Effects

Ming Yan1,2,*, Panyue Zhang1,2, Guangming Zeng1,2

ABSTRACT: This review focuses on the research Biological Nitrogen and Phosphorus Removal literatures published in 2015 relating to topics of thermal The short-term effect of temperature on the effects in water pollution control. This review is divided maximum biomass specific activity of anaerobic into the following sections: biological nitrogen and ammonium oxidizing (anammox) bacteria was reported by phosphorus removal, wastewater treatment for organic Lotti et al. (2015). The results indicated that for the conversion, industrial wastewater treatment, anaerobic anammox conversion, the temperature dependency could digestion of sewage sludge and solid waste, sludge biochar not be accurately modeled by one single Arrhenius preparation and application, pyrolysis of sewage sludge, coefficient as typically applied for other biological reduction heavy metal in sewage sludge and soil, and other processes. The temperature effect increased at lower issues of wastewater and sludge treatment. temperatures. Adapted anammox sludge had a higher

specific rate at lower temperature. Anammox sludge

KEYWORDS: thermal effects, biological nitrogen and cultivated in an aerated partial nitritation/anammox process phosphorus removal, wastewater treatment for organic and/or in biofilm seemed to be less influenced be a conversion, industrial wastewater treatment, anaerobic decrease in temperature than anammox sludge grown under digestion of sewage sludge and solid waste, sludge biochar non-arated conditions and/or in suspension. preparation and application, pyrolysis of sewage sludge, Lackner et al. (2015) compared partial nitritation- reduction heavy metal in sewage sludge and soil. anammox in two laboratory-scale reactors, a sequencing

batch reactor (SBR) and a moving bed biofilm reactor doi: 10.2175/106143016X14696400495730 (MBBR). Experiments were carried out with realistic

————————— seasonal temperature variations over a 1-year period. The

1*College of Environmental Science and Engineering, Hunan results revealed that both systems had to face the decrease

University, Changsha 410082, PR China; Tel. +86 13607488663; of ammonium conversion rates and nitrite accumulation at Fax. +86 731 88823701; e-mail: [email protected] a temperature lower than 12 °C. The SBR did not recover

2Key Laboratory of Environmental Biology and Pollution from the loss in anammox activity even when the

Control (Hunan University), Ministry of Education, Changsha temperature increased again. The MBBR only showed a

410082, PR China

short nitrite peak and recovered its initial ammonium (2015). The reactors were operated at a total nitrogen (TN) turnover when the temperature rose back to >15 °C. concentrations in the range of 5-20 mg/L. Anammox

The influence of temperature on the anammox activities reached 465 mg/L∙d at 29 °C with minimum process for high salinity wastewater was investigated by doubling time of 18 d. The Lower temperature of 12.5 °C

Xing et al. (2015). Four upflow anaerobic sludge blanket resulted in a significant decrease in activity to 46 mg/L∙d reactors were operated in parallel at ambient temperatures and the doubling time was 79 d. from 25 to 9 °C and thermostatic room temperatures of 35 A novel system integrating Johannesburg (JHB)

± 2 °C. The results demonstrated that low ambient and sulfur autotrophic denitrification (SAD) process was temperature and high sodium levels impaired the nitrogen proposed by Li et al. (2015), to enhance nitrogen removal removal performance of anammox granular sludge. The in treating low COD/TN ratio (COD 129 mg/L, TN 29 anaerobic ammonium-oxidizing bacteria gradually adapted mg/L on average) municipal wastewater at low temperature to a salt concentration of 15 g/L at low ambient temperature, (12.2 ± 0.5 °C). The results showed that under a HRT of

3 + and a nitrogen removal rate of 1.34 ± 0.12 kg N/m ∙d was 11.3 h, the average effluent COD, TN, and NH4 -N of JHB achieved, compared with 1.90 ± 0.01 kg N/m3∙d at a salt process were 32, 13.8, and 1.6 mg/L, respectively. It was concentration of 15 g/L and a temperature of 35 ± 2 °C. found that 87.0 % JHB effluent nitrogen was removed by

Partial nitritation for a low-strength wastewater SAD process under the most efficient nominal hydraulic

+ (70 mg NH4 –N) at low temperature was stably achieved in retention time (HRT) of 0.32 h. The SAD process effluent

+ an aerobic granular reactor in continuous mode (Isanta et of COD, TN, and NH4 –N were 21, 1.8, and 1.0 mg/L, al., 2015). The temperature progressively decreased from respectively. Most importantly, the JHB-SAD system could

30 to 12.5 °C, and a suitable effluent nitrite to ammonium achieve complete nitrogen removal theoretically as long as

+ concentrations ratio to a subsequent anammox reactor was the NH4 –N was sufficiently oxidized. maintained stable during 300 days at 12.5 °C. The average With inoculum sludge from a conventional applied nitrogen loading rate at 12.5 °C was 0.7 ± 0.3 g activated sludge wastewater treatment plant, the formation

N/L∙d, with an effluent nitrate concentration of only 2.5 ± of aerobic granular sludge (AGS) for simultaneous organic

- 0.7 mg NO3 –N/L. The biomass fraction of nitrite-oxidizing and nutrient removal in three SBRs at different high bacteria in the granular sludge decreased from 19% to only temperatures (30, 40 and 50 ± 1 °C) was studied by Halim

1% in 6 months of reactor operation at 12.5 °C. Nitrobacter et al. (2015). The complete cycle time of SBRs was 3 h. spp. were found as the dominant NOB population, whereas The results revealed that granules developed at 50 °C have

Nitrospira spp. were not detected. the highest average diameter of 3.36 mm, and the removal

Activity and growth of anammox biomass on efficiency of COD, ammonia and phosphate was 98.17%, municipal wastewater was researched by Michele et al. 94.45% and 72.46%, respectively. The study also

demonstrated that the AGS formed at high temperatures and the AAO showed a better performance at SRT of 5–25 was suitable for hot climate conditions. d under the same operating cost for its higher pollutant

Liu et al. (2015) studied the accumulation of removal efficiency and concentration of phosphorus- denitrifying polyphosphate-accumulating organisms accumulating organisms. Furthermore, the optimal

(DNPAOs) using an improved SBR system in which condition was obtained using mixed liquor recirculation of anaerobic-aerobic-anoxic and anaerobic-anoxic were 100%, returned activated sludge of 50%, and SRT of 16 d. adopted at a low temperature of 15 °C. The results Sayi-Ucar et al. (2015) conducted a long-term indicated that it was feasible to accumulate DNPAOs with study on the impact of high temperature on enhanced concurrent nitrogen and phosphorus removals in the biological phosphorus and nitrogen removal in membrane improved SBR system. Moreover, a DNPAOs strain was bioreactor. The MBR system was operated at relatively isolated and was identified as Acinetobacter sp. J6. The high temperatures (24–41 °C). The TP removal gradually strain J6 had the highest N and P removal rates under an increased from 50% up to 95% while the temperature original pH of 8.0, a total phosphorus (TP) concentration of descended from 41 to 24 °C. At high temperatures,

4.16 mg/L and a temperature of 15 °C. anaerobic volatile fatty acid (VFA) uptake occurred with

Dong et al. (2015) produced immobilized pellets low phosphorus release implying the competition of entrapping activated sludge in waterborne polyurethane, glycogen accumulating organisms (GAOs) with

+ and applied to treat ammonium (NH4 –N) synthetic polyphosphate accumulating organisms (PAOs). The gross wastewater in SBRs at low temperatures. The oxygen membrane flux was 43 LMH corresponding to the specific uptake rate of immobilized pellets reached 240.83±15.59 permeability of 413 LMH/bar at 39 °C in the MBR tank. mg O2/(L∙h), and the oxygen was primarily consumed by The specific permeability increased by the factor of 43% at the bacteria on the pellet surfaces (0–600 μm). The dosing 39 °C compared to that of 25 °C during long-term of the pellets (30 ml/L) into an SBR significantly improved operation. the nitrification efficiency at low temperatures of 7–11 °C, Ma et al. (2015) assessed a long-term

+ achieving an average NH4 –N removal of 84.09%, which is investigation of a novel electrochemical membrane higher than the removal of 67.46% observed for the control bioreactor (EMBR) for low-strength municipal wastewater group. treatment under low temperature. At lower temperatures

Modeling of multimode anaerobic/anoxic/aerobic (<10–15 °C), power production in the EMBR was

(AAO) wastewater treatment process at low temperature of negligible and therefore the integration did not improve the

12.5 °C was studied by Zhou et al. (2015). Influences of reactor performance. With the rebound of water sludge retention time (SRT) on effluent quality, functional temperature over 15–20 °C, efficient redox reactions were biomass and operating cost were evaluated for each mode, achieved in the EMBR, which subsequently resulted in

sludge reduction (27.3% lower than the control MBR) and removal by Scenedesmus sp. were obtained as model membrane fouling alleviation. The total nitrogen removal parameters. efficiency of the EMBR averaged 78.2% at high Cho et al. (2015) evaluated the factors temperatures, despite the decrease of organic loading rate influencing diversity and growth of indigenous algal of the feed for heterotrophic denitrification. Energy balance consortium cultivated on untreated municipal wastewater in analysis indicated that the total energy consumption of the a high rate algal pond (HRAP) for a period of 1 year.

EMBR decreased by 20% compared to that of the control Diversity analyses revealed the presence of Chlorophyta,

MBR (0.386 kWh/m3 wastewater). Cyanophyta and Bacillariophyta. Dominant microalgal

Huang et al. (2015) applied a deep-sea genera by biovolume in various seasons were Scenedesmus psychrotolerant bacteria to improve the performance of sp., Microcystis sp., and Chlorella sp. Scenedesmus sp., wastewater treatment by aerobic dynamic membrane persisted throughout the year but none of three strains co- bioreactors (ADMBR) at low temperature. Compared to the dominated with the other. The most significant factors control reactor, the bioaugmented reactor showed a shorter affecting genus dominance were temperature, inflow start-up period, and better wastewater treatment cyanophyta and organic carbon concentration. Cyanophyta performance at ≤15 °C for a sudden decrease, and ≤7 °C concentration affected microalgal biomass and diversity, for a gradual decrease in temperature. Severe membrane whereas temperature impacted biomass. fouling was not observed with bioaugmentation and the nonwoven fabric module was convenient to clean with tap Wastewater Treatment for Organic Conversion water. Fluorescence in situ hybridization (FISH) analysis Saha et al. (2015) hypothesized that methanol displayed the dominance of two inoculated strains at the could induce the growth of low-temperature resilient, low temperature of 5 °C. methanol utilizing, hydrogenotrophs in upflow anaerobic

The effect of temperature on microalgal sludge blanket (UASB) reactor. The results showed that ammonium uptake was investigated by Ruiz-Martínez et al. 0.04% (v/v) methanol increased methane up to 15 times

(2015). Experiments were carried out with a mixed culture and its effect was more pronounced at lower temperatures. of microalgae, composed mainly of Scenedesmus sp. within Both Methanobacteriales and Methanosetaceae grew the usual temperature working range in Mediterranean abundantly at low temperature, which indicated that climate (15–34 °C). Ammonium removal rates increased methanol induced the growth of both the hydrogenotrophic with temperature up to 26 °C and stabilized thereafter. and acetoclastic groups through direct and indirect routes,

Ratkowsky and Cardinal temperatures models respectively. demonstrated that the optimum (31.3 °C), minimum (8.8 °C) Wirth et al. (2015) examined the anaerobic and maximum (46.1 °C) temperatures for ammonium digestion of process liquor from hydrothermal

carbonization (HTC) of sewage sludge. The process was reduction in suspended biomass activity. Sequencing of performed at 37 °C (mesophilic) and 55 °C (thermophilic) 16S rRNA suggested that the biofilm's metabolic diversity on two identical continuously-fed anaerobic filters (26 L increased as the temperature decreased in response to a each) for 20 weeks. Significant differences in methane greater flux of complex organics into the biofilm due to production were not observed as both reactors yielded up to temperature-based suspended biomass inhibition. The

0.18 LCH4/gCOD. Increased temperature had no effect on the research demonstrated that AnMBR treatment of domestic steady-state COD removal efficiency with both reactors wastewater at very low temperatures is feasible. stabilized at 68–75%. Methanogenesis was identified as the Differential methanogenic protein expression speed-limiting step in anaerobic digestion of HTC liquor. associated with low-temperature anaerobic digestion (AD)

The operational feasibility of an anaerobic was described by Gunnigle et al. (2015). Comparative membrane bioreactor (AnMBR), consisting of an UASB investigation of key microbial groups underpinning reactor coupled to an ultrafiltration membrane unit was laboratory-scale AD bioreactors operated at 37, 15 and 7 assessed by Ozgun et al. (2015), to treat municipal °C was carried out. The results showed that δ- wastewater at two operational temperatures (25 and 15 °C). Proteobacteria were prevalent at 37°C, and their

The results showed that membrane fouling at 15 °C was abundance decreased dramatically at lower temperatures more severe than that at 25 °C. Higher COD and soluble with inverse trends observed for Bacteroidetes and microbial products (SMP) concentrations, lower mean Firmicutes. Methanobacteriales and Methanosaeta were particle diameter, and higher turbidity in the UASB effluent predominant at all temperatures investigated, while at lower temperature aggravated membrane fouling Methanomicrobiales abundance increased at 15 °C compared to the 25 °C operation. It is concluded that an compared with that at 37 and 7 °C. The temperature

AnMBR, consisting of a UASB coupled membrane unit, is changes resulted in the differential expression of proteins not found technically feasible for the treatment of involved in methanogenesis in all bioreactors. municipal wastewater at 15 °C, considering the rapid Arora et al. (2015) carried out a whole year deterioration of the filtration performance. experiment to make clear the effect of seasonal temperature

Smith et al. (2015) examined the effect of on pathogen removal efficacy of vermifilter for wastewater psychrophilic temperature on the AnMBR treatment of treatment. The higher BOD and COD removal was domestic wastewater. The evaluated temperatures were 15, observed during spring and autumn period with a mean

12, 9, 6, and 3 °C. The COD removal higher than 95% was temperature of 25–27 °C, and this temperature range was achieved when the temperatures was as low as 6 °C, but optimum for earthworm sp. Eisenia fetida for its activity, fell to 86% at 3 °C. As the temperature decreased, the growth and reproduction. However, during summer with a soluble COD in the bioreactor increased, suggesting a maximum temperature of 38–40 °C, the indicator bacteria

removal was maximum by 99.9%, Salmonella reduction by from 20 to 35 °C, and dropped dramatically to 78.38 % at

96.9% and Escherichia coli by 99.3%. The pathogen 40 °C, presumably because the genus of Dehalobacter, a removal efficacy of vermifiltration increased with the kind of bacteria with the ability to dechlorinate TCE to the increase in temperature, which implied that temperature corresponding chlorinated products, was not detected at 40 had a significant contribution to the pathogen removal °C efficiency of vermifiltration. Yang et al. (2015) carried out a study to examine

Impact of temperature and photoperiod on the effect of novel ceramic media from sludge and coal anaerobic biodegradability of microalgae grown in urban cinder and straw on the combined up-flow anaerobic bio- wastewater was investigated by González-Fernández et al. filter (UAF) and up-flow biological aerated filter (UBAF)

(2015). Experiments were carried out under three different system to treat the synthetic wastewater containing scenarios (I: 23 °C/14 h illumination, II: 15 °C/14 h and III: tetracycline (TET) at low temperature of 16 °C. Due to the

15 °C/11 h). With respect to biomass cultivation, novel ceramics fillers, the start periods of the UAF and temperature affected biomass productivity but not final UBAF were shortening to 42 and 10 d. Moreover, biomass concentration. Carbohydrates accumulation compared to conventional reactor, the new system had prevailed under Scenario I while low temperature (Scenario advantages of high processing efficiency, high organic

II) and short photoperiod (Scenario III) increased lipid and load, strong shock and tetracycline resistance. When

+ protein content. Comparison between the theoretically original influent COD, NH4 -N and TET were 4000, 200

+ calculated and experimentally obtained methane yield and 45 mg/L, the total COD, NH4 -N and TET reductions values showed that biomass collected at Scenario III only could reach to 97%, 99% and 89%. Furthermore, the low reached 36.1% of the theoretical methane yield achievable temperature did not influence the system. compared to 46.5% attained with the biomass collected at High-temperature Fenton oxidation was applied

Scenario I. by Díaz de Tuesta et al. (2015), to treat sulfonation plant

wastewater. The results demonstrated that the high-

Industrial Wastewater Treatment temperature Fenton oxidation provided a better

The effect of temperature on trichloroethylene performance than other advanced oxidation processes. The

(TCE) removal in an up-flow anaerobic sludge blanket optimal conditions of Fenton oxidation were the reactor was studied by Zhang et al. (2015) within a temperature of 94 °C, 70% of the stoichiometric H2O2 dose temperature range from 20 to 40 °C. There was a rise in relative to initial COD, 1 h reaction time and the pH of the

COD removal efficiency from 20 to 35 °C and a decline wastewater as received (1.7) to achieve the discharge limits when temperature further increased to 40 °C. The TCE into the exiting activated sludge plant of the petrochemical removal efficiency increased with temperature varying complex where the sulfonation plant is located.

A bench-scale test was conducted with a novel batch reactor with acetate as the carbon source. Results multi-stage loop membrane bioreactor (MsLMBR) to treat showed that NO and N2O emissions increased when the chemical synthesis-based pharmaceutical wastewater temperature decreased. NO emissions appeared only at 10 containing 7-ACA (Chen et al., 2015). Results showed that and 5 °C, with respectively 8% and 18% of the total for MsLMBR1 at 15 °C, MsLMBR2 at 25 °C and denitrified nitrogen. N2O emissions increased from 13% to

MsLMBR3 at 35 °C, the average total COD (TCOD) of the 40% then 82% of the total denitrified nitrogen at 20, 10 and effluent were all less than 80 mg/L. For MsLMBR2 and 5 °C, respectively (Adouani et al., 2015).

MsLMBR3, the microorganisms had better microbial The challenge of keeping downstream activities and drug-resistances, and the biological removal temperatures below established maxima in the face of was given priority to TCOD removal. But for MsLMBR1, climate-induced variations in stream discharge and there was no significant difference between biological temperature was analyzed (Huisenga and Travis, 2015). removal and physical removal at the early stage. The 7- Changes in receiving waters, especially stream temperature

ACA pharmaceutical wastewater was effectively treated in or discharge, may have a significant effect on permit levels a MsLMBR system, which also performed well at low for a wastewater treatment facility. Therefore, temperature. understanding the effects of climate variation on stream

Effects of hydraulic retention time, temperature, discharge and temperature is important in assessing and organic load on two horizontal subsurface flow potential changes to future wastewater effluent permits. constructed wetland (CW) units (one planted and one Wastewater heat recovery applications are unplanted) treating secondary cheese whey were discussed becoming widespread in energy saving applications. Culha by Sultana et al. (2015). Tested temperature was from 2.4 et al. (2015) reviewed a sustainable and low emissions to 32.9 °C. CWs successfully treated secondary cheese operation in air conditioning and heating processes whey and provided COD effluent concentrations below EU achieved by harvesting the otherwise wasted energy in legislation, when hydraulic residence time was above 2 d wastewater through specially designed heat exchangers, and COD influent concentration ranged from 1200 to lying at the core of heat pumps. In their study, wastewater

3500 mg/L. The temperature significantly affected COD heat exchangers in wastewater source heat pump removal only in unplanted unit. applications was presented, and wastewater heat

exchangers were classified in detail based on multiple

Other Issues in Wastewater Treatment features, including utilization and construction

Influence of temperature on N2O and NO methodology. The potential of wastewater, types of emissions during wastewater denitrification was wastewater source heat pumps, and their applications are investigated. Experiments were carried out at pH 7 in a briefly discussed.

sludge based on an explicit reaction scheme considering

+ Anaerobic Digestion of Sewage Sludge and Solid exact intermediates including protein, saccharide, NH4 –N

Waste and acetic acid. The parameters were estimated by a series

Abelleira-Pereira et al. (2015) studied the of kinetic data at a temperature range of 180–300 °C. The advanced thermal hydrolysis (ATH) of sludge for protein and saccharide are the primary intermediates in the improvement of mesophilic anaerobic digestion initial stage of HTD resulting from the fast reduction of pretreatments. ATH is a novel anaerobic digestion biomass. The oxidation processes of macromolecular pretreatment based on a thermal hydrolysis (TH) process products to acetic acid are highly dependent on reaction plus hydrogen peroxide (H2O2) addition that takes temperature and dramatically restrained when temperature advantage of a peroxidation/direct steam injection is below 220 °C. synergistic effect. Results showed that both TH and ATH Hao and Wang (2015) studied the microbial patently improved methane production in subsequent responses to different fermentation temperatures during the mesophilic biochemical methane potential (BMP) tests in volatile fatty acids productions by mesophilic and comparison with control BMP tests (raw secondary sewage thermophilic sludge fermentation. The results showed that sludge). A promising result was obtained since ATH, thermophilic fermentation led to 10-fold more operated at temperature (115 °C), pretreatment time (5 min) accumulation of VFAs compared to mesophilic and pressure (1 bar) considerably below those typically fermentation. α-glucosidase and protease had much higher used in TH (170 °C, 30 min, 8 bar), managed to enhance activities in thermophilic reactor, especially protease. the methane production in subsequent mesophilic BMP Illumina sequencing manifested that raising fermentation tests. temperature increased the abundances of Clostridiaceae,

Riau et al. (2015) applied ultrasonic method to Microthrixaceae and Thermotogaceae, which could pretreat waste activated sludge by upgrading temperature- facilitate either hydrolysis or acidification. Real-time PCR phased anaerobic digestion (TPAD). The research found no analysis demonstrated that under thermophilic condition the significant differences in the overall performance of the relative abundance of homoacetogens increased in batch

TPAD process, but different behaviours were observed tests and reached higher level at stable fermentation, between the thermophilic and mesophilic stages. Total whereas under mesophilic condition it only increased methane production was enhanced by more than 50% and slightly in batch tests. the volatile solid removal increased by 13% in comparison Microbial diversity in an innovative to the TPAD control process. mesophilic/thermophilic temperature-phased anaerobic

Yin et al. (2015) developed a detailed kinetic digestion of sludge was investigated by Gagliano et al. model for hydrothermal decomposition (HTD) of sewage (2015). The increase of digestion temperature drastically

affected the microbial composition and selected specialized temperature, pressure and NaOH dosage. The best biomass. Hydrogenotrophic Methanobacteriales and the conditions for organic matter solubilisation were 160 °C, 3 protein fermentative bacterium Coprothermobacter spp. g NaOH/L, 6.5 bar and 30 min, with yields in terms of were identified in the thermophilic anaerobic biomass. dissolved organic carbon (DOC), SCOD, total VFA (TVFA)

Species richness was lower under thermophilic conditions and acidogenic substrate as carbon (ASC) of 176%, 123%, compared with that estimated in mesophilic samples, and it 119% and 178% respectively. was flanked by similar trend of the evenness indicating that Fernández-Rodríguez et al. (2015) carried out a thermophilic communities may be therefore more temperature-phased anaerobic digestion (TPAD) without susceptible to sudden changes and less prompt to adapting microbiological separation (thermophilic 55 °C–mesophilic to operative variations. 35 °C) to the biomethanation of organic fraction of

Ariunbaatar et al. (2015) studied the municipal solid waste (OFMSW). The higher organic enhancement of mesophilic anaerobic digestion of food matter removal (VS removal 82–85%) and the maximum waste by substrate thermal (heating the food waste in a specific growth rates of microorganisms (0.31–0.43 d-1) separate chamber) and thermophilic (heating the full were obtained for thermophilic phase operation at 5 and 4 d, reactor content containing both food waste and inoculum) respectively. It could be concluded that the optimum time pretreatments at 50, 60, 70 and 80 °C. Pretreatments at a for the thermophilic first-phase in TPAD would be between lower temperature (50 °C) and a shorter time (<12 h) had a 5 and 4 d. positive effect on the anaerobic digestion process. The Yan et al. (2015) investigated the effects of initial highest enhancement of the biomethane production with an substrate concentration (ISC), C/N ratio, and temperature increase by 44–46% was achieved with a thermophilic on the biogasification of solid-state AD (SS-AD) from pretreatment at 50 °C for 6–12 h or a thermal pretreatment composting rice straw. Rice straw compounds, such as at 80 °C for 1.5 h. Thermophilic pretreatments at higher lignin, cellulose, and hemicellulose, were significantly temperatures (>55 °C) and longer operating times (>12 h) degraded after composting. A significant interactive effect yielded higher soluble COD (SCOD), but had a negative of temperature, ISC and C/N ratio was found on the effect on the methanogenic activity. biogasification of SS-AD of composting RS, and a

Thermochemical pretreatments have been applied maximum biogas production was achieved at 35.6 °C, with on the organic fraction of municipal solid waste (OFMSW) a 20% ISC and a C/N ratio of 29.6:1. High-throughput coming from a full-scale mechanical-biological treatment sequencing analysis indicated that microbial communities

(MBT) plant, in order to pre-hydrolyze the waste and in the SS-AD mainly consist of Methanobacteria, improve the organic matter solubilisation (Álvarez-Gallego Bacteroidia, Clostridia, Betaproteobacteria, and et al., 2015). The process variables analyzed were Gammaproteobacteria.

investigated to check their CO and SO2 emissions in a hot

Pyrolysis of Sewage Sludge flue gas flow, and the recycle sewage sludge char was used

The polycyclic aromatic hydrocarbons (PAHs) as flue gas De-NOx catalyst within low temperature ranges toxicity and sorption behaviour of biochars prepared from (Chen et al., 2015). The chars produced at 750 and 800 °C pyrolysis of paper mill effluent treatment plant sludge in were highly temperature- and oxidant-resistant and their temperature range 200–700 °C was studied by Devi and CO emissions were considerably inhibited in the

Saroha (2015). The sorption behaviour was found to temperature range of 100 to 400 °C with oxygen level of 5– depend on the degree of carbonization, where the fractions 10%, at the same time, De-NOx efficiencies were increased of carbonized and uncarbonized organic content in the by 25% to 50%. The char obtained at 750 °C had the best biochars act as an adsorption media and partition media, ability to remove NOx both as an absorbent and as a respectively. The risk assessment for the 16 priority EPA catalyst.

PAHs present in the biochar matrix was performed and it Lu et al. (2015) investigated the characteristic of was found that the concentrations of the PAHs in the heavy metals (Pb, Zn, Cu, Cd, Cr, Ni and As) in biochar biochar were within the permissible limits prescribed by derived from sewage sludge at different pyrolysis

US EPA (except BC400 and BC500 for high molecular temperatures (300, 400, 500, 600 and 700 °C). The results weight PAHs). showed that a great percentage of the heavy metals

Yuan et al. (2015) examined the influence of remained in biochar, the concentrations of heavy metals in pyrolysis temperature on the physical and chemical biochar (except Cd at a temperature of 700 °C) were higher properties of biochar made from sewage sludge. Biochar than that in sludge, and the enrichment of the heavy metals yield decreased and its pore structure developed with the in biochar enhanced with the pyrolysis temperature. increase of temperature from 300 to 700 °C. Biochar However, the potential risk of biochar on soil and produced at 300 °C was acidic whereas at higher groundwater contamination was lower than sewage sludge. temperatures it was alkaline. Fewer dissolved salts were Sewage sludge (SS) was pyrolyzed in a fixed bed contained in the biochars produced at higher temperatures. reactor from 400 to 600 °C using composite alumina (CA)

The rich nutrients, other than nitrogen, were intensified as catalyst (Sun et al., 2015). The product yields and with the temperature rise. The leaching toxicity of Pb, Zn, component distribution of non-condensable gas were more

Ni, Cd, As, Cu and Cr in the biochars was lower than that sensitive to the change of temperature, and the maximum in the sewage sludge although the pyrolysis process liquid yield of 48.44 wt.% and maximum useable energy of enriched the heavy metals in the biochars. liquid of 3871 kJ/kg sludge were observed at 500 °C with

Sewage sludge chars produced at four different 1/5 CA/SS (mass ratio). The gas chromatography-mass pyrolysis temperatures (550, 650, 750 and 800 °C) were spectrometry results showed that the increase of

temperature enhanced devolatilization of organic matter metals zinc, copper, chromium, cadmium and nickel and promoted cyclization and aromatization of aliphatics. decreased by >50% in both batches. Lead got leached out

The effects of CA on decomposition of fatty acids and only when sulfur was used as the energy source. formation of aromatics were similar to that of temperature. Alicyclobacillus tolerans was found to be the

This means that the reaction temperature could be lowered microorganism responsible for lowering the pH in both the by introducing CA, which has a positive effect on reducing reactors at thermophilic temperature. The indicator energy consumption. organism count was also below the maximum permissible

Ridout et al. (2015) discussed the influence of limit making sludge suitable for agricultural use. reactor temperature and pellet size on the pyrolysis Mao et al. (2015) discussed the impact of efficiency of paper waste sludge (PWS). Maximum bio-oil temperature on Cr(VI) formation and reduction during yields of 44.5 ± 1.7 daf, wt% at 400 °C, and 59.9 ± 4.1 daf, heating of chromium-containing sludge in the presence of wt% at 340 °C, for an intermediate pellet size of 4.84 ± CaO. The result showed that CaO promoted Cr(III)

0.15 mm, were attained from the conversion of the low and oxidation, however, its influence is very dependent on high ash PWS (8.5 and 46.7 wt%), respectively. The low heating temperature. From 200–400 °C, the presence of optimal reactor temperatures, as well as the high bio-oil CaO facilitated formation of intermediate product Cr2O3+x yields, make valorisation via fast pyrolysis conversion containing Cr(VI) during dehydration of chromium hydrate, promising. Due to the promotion of exothermic reactions while Cr2O3+x would decompose as temperature over for high heating rates, using smaller pellet sizes increased 400 °C, accompanied by part of Cr(VI) being reduced to non-condensable gas yield, which corresponded to a Cr(III). From 500 to 900 °C, Cr(III) reacted with CaO to decrease in the bio-oil yield form a leachable CaCrO4 product. This product was stable

. and a prolonged heating time did not reduce the amount of

Reduction of Heavy Metal in Sewage Sludge and Cr(VI) significantly. At 1000–1200 °C, part of CaCrO4 was

Soil reduced to Ca(CrO2)2 in 1 h. While extended heating time

Mehrotra et al. (2015) proposed a possibility of above 1 h resulted in the Ca(CrO2)2 being oxidized using simultaneous sewage sludge digestion and metal reversibly to CaCrO4 at 1200 °C. Since CaCrO4 is leaching (SSDML) process at the thermophilic temperature thermodynamically less stable over 1000 °C, MgO could to remove heavy metals and suspended solids from sewage induce CaCrO4 to be reduced into MgCr2O4 at around sludge. The SSDML process was carried out at 50 °C 900 °C, lower than that for the reduction from CaCrO4 into

(thermophilic) by using ferrous sulfate or sulfur as the Ca(CrO2)2. energy source in two reactors. The concentration of volatile Thermal treatment is a promising technology for suspended solids reduced by >40%, while that of heavy the remediation of mercury contaminated soils, but it often

requires high energy input at heating temperatures above correlated to the variation of these biopolymers. The

600 °C, and the treated soil is not suitable for agricultural filtrates collected above 150 °C were found to be acidic. reuse. Ma et al. (2015) developed a novel method for the Białobrzewskia et al. (2015) performed a thermal treatment of mercury contaminated soils with the mathematical model to simulate the sewage sludge-straw facilitation of citric acid (CA). When CA/Hg molar ratio composting process integrating different heat generation was 15 as the optimum dosage, the mercury concentration capacities of mesophilic and thermophilic microorganisms. in soils was successfully reduced from 134 mg/kg to 1.1 The model incorporates two microbial groups (mesophiles mg/kg when treated at 400 °C for 60 min and the treated and thermophiles) characterized by different capacities of soil retained most of its original soil physiochemical heat generation. The parameters modeled over a period of properties. Citric acid was found to provide an acidic 36 d. The coefficients of metabolic heat generation for environment which enhanced the volatilization of mercury. mesophiles were 4.32 × 106 and 6.93 × 106 J/kg, for winter

This method is expected to reduce energy input by 35% and summer seasons, respectively. However, for comparing to the traditional thermal treatment method. thermophiles, they were comparable for both seasons

reaching 10.91 × 106 and 10.51 × 106 J/kg. In the model,

Other Issues in Sewage Sludge and Biowaste significant parameters for microbial growth control were Treatment temperature and the content of easily hydrolysable Wang et al. (2015) evaluated the dewatering substrate. The proposed model provided a satisfactory fit to performance and the characteristics of obtained products experimental data captured for cuboid-shaped bioreactors (hydrothermal sludge, hydrochar and filtrate). The sludge with forced aeration. dewatering was conducted with hydrothermal treatment coupled with mechanical expression in two separate cells. References The results showed that harsher hydrothermal treatment led Abelleira-Pereira, J. M.; Pérez-Elvira, S. I.; Sánchez-Oneto, J.; de to more water removal, and mechanical pressure became la Cruz, R.; Portela, J. R.; Nebot, E. (2015) Enhancement of less significant as the temperature increased. The higher Methane Production in Mesophilic Anaerobic Digestion of heating value correlated well with carbon content of sludge, Secondary Sewage Sludge by Advanced Thermal which increased by 4.8% for hydrothermal sludge at Hydrolysis Pretreatment. Water Res., 71, 330–340.

210 °C for 60 min and significantly decreased by 15.4% for Adouani, N.; Limousy, L.; Lendormi, T.; Sire, O. (2015) N2O and hydrochar after 6.0 MPa for 20 min. The solubilization and NO Emissions during Wastewater Denitrification Step: Influence of Temperature on the Biological Process. C. R. decomposition of proteins, polysaccharides and DNA were Chim., 18, 15–22. determined to be temperature and residence time dependent, Álvarez-Gallego, C. J.; Fdez-Güelfo, L. A. (2015) and the improvement of dewaterability was closely Thermochemical Pretreatments of Organic Fraction of

Municipal Solid Waste from a Mechanical-Biological Effluent Treatment Plant Sludge. Bioresour. Technol., 192,

Treatment Plant. Int. J. Mol. Sci., 16(2), 3769–3782. 312–320.

Ariunbaatar, J.; Panico, A.; Yeh, D. H.; Pirozzi, F.; Lens, P. N. L. Díaz de Tuesta, J. L.; García-Figueruelo, C.; Quintanilla, A.;

(2015) Enhanced Mesophilic Anaerobic Digestion of Food Casas, J. A.; Rodriguez, J. J. (2015) Application of High-

Waste by Thermal Pretreatment: Substrate Versus Digestate Temperature Fenton Oxidation for the Treatment of

Heating. Waste Manage., 46, 176–181. Sulfonation Plant Wastewater. J. Chem. Technol.

Arora, S. A.; Kazmi, A. (2015) The Effect of Seasonal Biotechnol., 90, 1839–1846.

Temperature on Pathogen Removal Efficacy of Vermifilter Dong, W.; Lu, G.; Yan, L.; Zhang, Z.; Zhang Y. (2016)

for Wastewater Treatment. Water Res., 74, 88–99. Characteristics of Pellets with Immobilized Activated

Białobrzewskia, I.; Mikš-Krajnikb, M.; Dachd, J.; Markowskia, Sludge and its Performance in Increasing Nitrification in

M.; Czekaład, W.; Głuchowskae, K. (2015) Model of the Sequencing Batch Reactors at Low Temperatures. J.

Sewage Sludge-Straw Composting Process Integrating Environ. Sci., 42, 202-209.

Different Heat Generation Capacities of Mesophilic and Fernández-Rodrígueza, J.; Pérezb, M.; Romeroc, L. I. (2015)

Thermophilic Microorganisms. Waste Manage., 43, 72–83. Temperature-Phased Anaerobic Digestion of Industrial

Chen, H.; Chen, D. Z.; Hong, L.; Dou, X. M. (2015) Recycle Organic Fraction of Municipal Solid Waste: A Batch Study.

Sewage Sludge Char as Flue Gas De-NOx Catalyst within Chem. Eng. J., 270, 597–604.

Low Temperature Ranges. Energy Procedia, 66, 45–48. Gagliano, M. C.; Braguglia, C. M.; Gallipoli, A. (2015) Microbial

Chen, Z.; He, Z.; Hu, D.; Cui, Y.; Ran, C.; Ge, H. (2015) Effect of Diversity in Innovative Mesophilic/Thermophilic

Temperature on Treating Chemical Synthesis-Based Temperature-Phased Anaerobic Digestion of Sludge.

Pharmaceutical Wastewater Containing 7-ACA by a Novel Environ. Sci. Pollut. Res., 22, 7339–7348.

Multi-Stage Loop Membrane Bioreactor. J. Chem. Technol. González-Fernández, C.; Mahdy, A.; Ballesteros, I. (2015) Impact

Biotechnol., 90, 1002–1012. . of Temperature and Photoperiod on Anaerobic

Cho, D. H.; Ramanan, R.; Heo, J.; Kang, Z.; Kim, B. H. (2015) Biodegradability of Microalgae Grown in Urban

Organic Carbon, Influent Microbial Diversity and Wastewater. Int. Biodeterior. Biodegrad., 106, 16–23.

Temperature Strongly Influence Algal Diversity and Gunnigle, E.; Siggins, A.; Botting, C. H. (2015) Low-Temperature

Biomass in Raceway Ponds Treating Raw Municipal Anaerobic Digestion is Associated with Differential

Wastewater. Bioresour. Technol., 191, 481–487. Methanogenic Protein Expression. FEMS Microbiol. Lett.,

Culha, O.; Gunerhan, H.; Biyik, E.; Ekren, O; Hepbasli, A. (2015) doi:10.1093/femsle/fnv059.

Heat Exchanger Applications in Wastewater Source Heat Halim, M. H. A.; Anuar, A. N.; Azmi, S. I.; Jamal, N. S. A.;

Pumps for Buildings: A key Review. Energ. Buildings, 104, Wahab, N. A.; Ujang, Z.; Shraim, A.; Bob, M. M. (2015)

215–232. Aerobic Sludge Granulation at High Temperatures for

Devi, P.; Saroha, A. K. (2015) Effect of Pyrolysis Temperature on Domestic Wastewater Treatment. Bioresour. Technol., 185,

Polycyclic Aromatic Hydrocarbons Toxicity and Sorption 445–449.

Behaviour of Biochars Prepared by Pyrolysis of Paper Mill Hao, J. X.; Wang, H. (2015) Volatile Fatty Acids Productions by

Mesophilic and Thermophilic Sludge Fermentation:

Biological Responses to Fermentation Temperature. Lu, T.; Yuan, H. R.; Wang, Y. Z.; Huang, H. Y.; Chen, Y. (2015)

Bioresour. Technol., 175, 367–373. Characteristic of Heavy Metals in Biochar Derived from

Huang, Z. S.; Qie, Y.; Wang, Z.; Zhang, Y.; Zhou, W. (2015) Sewage Sludge. J. Mater Cycles Waste Manage., 1–9.

Application of Deep-Sea Psychrotolerant Bacteria in Ma, F. J.; Peng, C. S.; Hou, D. Y.; Wu, B.; Zhang, Q.; Li, F. S.;

Wastewater Treatment by Aerobic Dynamic Membrane Gu, Q. B. (2015) Citric Acid Facilitated Thermal Treatment:

Bioreactors at Low Temperature. J. Membr. Sci., 475, 47– An Innovative Method for the Remediation of Mercury

56. Contaminated Soil. J. Hazard. Mater., 300, 546–552.

Huisenga, M. T.; Travis, W. R. (2015) Climate Variability and the Ma, J. X.; Wang, Z. W.; He, D.; Li, Y. X.; Wu, Z. C. (2015) Long-

Sensitivity of Downstream Temperature to Treated Term Investigation of a Novel Electrochemical Membrane

Wastewater Discharge: a Simulation Analysis. Environment Bioreactor for Low-Strength Municipal Wastewater

Systems and Decisions, 35, 11–21. Treatment. Water Res., 78, 98–110.

Isanta, E.; Reino, C.; Carrera, J.; Pérez, J. (2015) Stable Partial Mao, L.; Gao, B.; Deng, N.; Zhai, J.; Zhao, Y.; Li, Q.; Cui, H.

Nitritation for Low-strength Wastewater at Low (2015) The Role of Temperature on Cr(VI) Formation and

Temperature in an Aerobic Granular Reactor. Water Res., Reduction during Heating of Chromium-containing Sludge

80, 149–158. in the Presence of CaO. Chemosphere, 138, 197–204.

Lackner S.; Welker S.; Gilbert E. M.; Horn H. (2015) Influence of Mehrotra, A., Kundu, K., Sreekrishnan, T. R. (2016)

Seasonal Temperature Fluctuations on Two Different Partial Decontamination of Heavy Metal Laden Sewage Sludge

Nitritation-Anammox Reactors Treating Mainstream with Simultaneous Solids Reduction Using Thermophilic

Municipal Wastewater. Water Sci. Technol., 72, 1358–1363. Sulfur and Ferrous Oxidizing Species. J. Environ. Manage.,

Li, H. B.; Zhou, B. H.; Tian, Z. Y.; Song, Y. H.; Xiang, L. C.; 167, 228-235

Wang, S. Y.; Sun, C. (2015) Efficient Biological Nitrogen Michele, L.; David, G.; Weissbrodt, I. S.; Orlane, R.; Jeppe, L. N.;

Removal by Johannesburg-Sulfur Autotrophic Eberhard M.; Adriano, J. (2015) Activity and growth of

Denitrification from Low COD/TN Ratio Municipal anammox biomass on aerobically pre-treated municipal

Wastewater at Low Temperature. Environ. Earth Sci., 73, wastewater. Water Res., 80, 325–336.

5027–5035. Ozgun, H.; Tao, Y.; Ersahin, M. E.; Zhou, Z.; Gimenez, J. B.

Liu, S.; Li, J. Z. (2015) Accumulation and Isolation of (2015) Impact of Temperature on Feed-Flow Characteristics

Simultaneous Denitrifying Polyphosphate-Accumulating and Filtration Performance of an Upflow Anaerobic Sludge

Organisms in an Improved Sequencing Batch Reactor Blanket Coupled Ultrafiltration Membrane Treating

System at Low Temperature. Int. Biodeterior. Biodegrad., Municipal Wastewater. Water Res., 83, 71–83.

100, 140–148. Riau, V.; De la Rubia, M. A.; Pérez, M. (2015) Upgrading the

Lotti, T.; Kleerebezem, R.; van Loosdrecht, M. C. M. (2015) Temperature-Phased Anaerobic Digestion of Waste

Effect of Temperature Change on Anammox Activity. Activated Sludge by Ultrasonic Pretreatment. Chem. Eng.

Biotechnol. Bioeng., 112, 98–103. J., 259, 672–681.

Ridout, A. J.; Carrier1, M.; Görgens, J. (2015) Fast Pyrolysis of

Low and High Ash Paper Waste Sludge: Influence of

Reactor Temperature and Pellet Size. J. Anal. Appl. Anaerobic Treatment of Process Liquor from Hydrothermal

Pyrolysis, 111, 64–75. Carbonization of Sewage Sludge. Bioresour. Technol., 198,

Ruiz-Martíneza, A.; Serraltaa, J.; Secob, A.; Ferrera, J. (2015) 215–222.

Effect of Temperature on Ammonium Removal in Xing, B. S.; Guo, Q.; Yang, G. F.; Zhang, J. (2015) The Influences

Scenedesmus sp. Bioresour. Technol., 191, 346–349. of Temperature, Salt and Calcium Concentration on the

Saha, S.; Badhe, N.; De Vrieze, J.; Biswas, R. (2015) Methanol Performance of Anaerobic Ammonium Oxidation

Induces Low Temperature Resilient Methanogens and (Anammox) Process. Chem. Eng. J., 265, 58–66.

Improves Methane Generation from Domestic Wastewater Yan, Z.; Song, Z.; Li, D.; Yuan, Y.; Liu, X.; Zheng, T. (2015) The

at Low to Moderate Temperatures. Bioresour. Technol., Effects of Initial Substrate Concentration, C/N Ratio, and

189, 370–378. Temperature on Solid-State Anaerobic Digestion from

Sayi-Ucar, N.; Sarioglu, M.; Insel, G.; Cokgor, E. U.; Orhon, D.; Composting Rice Straw. Bioresour. Technol., 177, 266–273.

van Loosdrecht, M. C. M. (2015) Long-Term Study on the Yang, K. L.; Yue, Q. Y.; Han, W.; Kong, J. J.; Gao, B. Y.; Zhao,

Impact of Temperature on Enhanced Biological Phosphorus P.; Duan, L. (2015) Effect of Novel Sludge and Coal Cinder

and Nitrogen Removal in Membrane Bioreactor. Water Ceramic Media in Combined Anaerobic–aerobic Bio-filter

Res., 84, 8–17. for Tetracycline Wastewater Treatment at Low

Smith, A. L.; Skerlosab, S. J.; Raskin, L. (2015) Anaerobic Temperature. Chem. Eng. J., 277, 130–139.

Membrane Bioreactor Treatment of Domestic Wastewater at Yin, F. J.; Chen, H. Z.; Xu, G. H.; Wang, G. W.; Xu, Y. J. (2015)

Psychrophilic Temperatures Ranging from 15°C to 3°C . A Detailed Kinetic Model for the Hydrothermal

Water Res. Technol., 1, 56–64. Decomposition Process of Sewage Sludge. Bioresour.

Sultana, M. Y.; Mourti, C.; Tatoulis, T. (2015) Effect of Hydraulic Technol., 198, 351–357.

Retention Time, Temperature, and Organic Load on a Yuan, H.; Lu, T.; Huang, H.; Zhao, D.; Kobayashi, N. (2015)

Horizontal Subsurface Flow Constructed Wetland Treating Influence of Pyrolysis Temperature on Physical and

Cheese Whey Wastewater. J. Chem. Technol. Biotechnol., Chemical Properties of Biochar Made from Sewage Sludge.

91, 726–732. J. Anal. Appl. Pyrolysis, 112, 284–289.

Sun, Y.; Jin, B. S.; Wu, W.; Zuo, W.; Zhang, Y.; Zhang, Y.; Zhang, Y.; Hu, M.; Li, P.; Wang, X.; Meng, Q. (2015)

Huang, Y. J. (2015) Effects of Temperature and Composite Trichloroethylene Removal and Bacterial Variations in the

Alumina on Pyrolysis of Sewage Sludge. J. Environ. Sci., Up-Flow Anaerobic Sludge Blanket Reactor in Response to

30, 1–8. Temperature Shifts. Appl. Microbiol. Biotechnol., 99, 6091–

Wang, L. P.; Li, A. M. (2015) Hydrothermal Treatment Coupled 6102

with Mechanical Expression at Increased Temperature for Zhou, Z.; Shen, X. L.; Jiang, L. M.; Wu, Z. C.; Wang, Z. W.; Ren,

Excess Sludge Dewatering: The Dewatering Performance W. C.; Hu, D. L. (2015) Modeling of Multimode

and the Characteristics of Products. Water Res., 68, 291– Anaerobic/Anoxic/Aerobic Wastewater Treatment Process

303. at Low Temperature for Process Optimization. Chem. Eng.

Wirth, B.; Reza, T.; Mumme, J. (2015) Influence of Digestion J., 281, 644–650.

Temperature and Organic Loading Rate on the Continuous